EP0608244B1 - Method for the manufacture of tall oils - Google Patents
Method for the manufacture of tall oils Download PDFInfo
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- EP0608244B1 EP0608244B1 EP92917068A EP92917068A EP0608244B1 EP 0608244 B1 EP0608244 B1 EP 0608244B1 EP 92917068 A EP92917068 A EP 92917068A EP 92917068 A EP92917068 A EP 92917068A EP 0608244 B1 EP0608244 B1 EP 0608244B1
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- Prior art keywords
- tall oil
- oil soap
- solution
- aqueous
- electrolysis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D57/00—Separation, other than separation of solids, not fully covered by a single other group or subclass, e.g. B03C
- B01D57/02—Separation, other than separation of solids, not fully covered by a single other group or subclass, e.g. B03C by electrophoresis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
- B01D17/06—Separation of liquids from each other by electricity
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B3/00—Electrolytic production of organic compounds
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/0007—Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for
Definitions
- the present invention relates to the direct conversion of tall oil soap to tall oil.
- Coniferous woods especially pine, contain among other components, lignin, resin acids and long-chain fatty acids. Crude tall oil, a mixture of the resin and fatty acids, is produced as a chemical by-product of the kraft pulping process.
- the initial weak black liquor (at about 15% solids) is filtered to remove fiber and is passed into a weak liquor skimmer. Thirty per cent (30%) to 70% of the available black liquor soap is skimmed off. The black liquor then passes through several stages of evaporative concentration to raise the solids content to 25-30%. The black liquor then passes through a second skimmer from which the remaining 30-70% of soap is skimmed off. The black liquor finally passes through more stages of evaporative concentration to raise the solids to 50-60%. It is then fed to a recovery furnace to be burned. Burning the organic content of the black liquor provides energy for the paper making process and reconstitutes the inorganic chemicals for reuse in fresh pulping liquors (Foran, C. D., "Black Liquor Soap Recovery Methods Employed by Union Camp," Naval Stores Review, 94, 14 (1984) ).
- black liquor soap is degassed (or concentrated) to remove foam and is then settled to decant out excess residual black liquor.
- the separated tall oil soap is then normally acidulated with sulfuric acid to form crude tall oil, which can be refined by vacuum fractionation to form tall oil fatty acids and tall oil rosin.
- the fatty acids and rosin are used in numerous industrial applications, including the preparation of polyamides, rosin resins, adhesive and epoxy compositions.
- the acidulation process comprised the addition of sulfuric acid (H2SO4) to the tall oil soap to produce crude tall oil and Na2SO4 salt cake solution.
- H2SO4 sulfuric acid
- Wong also discussed tall oil soap acidulation and sulfur balance problems in kraft mills (Wong, A., Naval Stores Review, 94 , (3), 8 (1984) ). Wong reported the same problems associated with the salt cake from the acidulation of the tall oil soap as did Twiss. Wong proposed the replacement of H2SO4 used in soap acidulation with chlorine dioxide generator effluent to lower the sulfur input into the mill liquor system. However, the reduced sulfur input would still be higher than the losses in the mill by about 10%.
- caustic soda must be used to replace sodium lost in the kraft pulping process. Not only is the caustic soda more expensive than the H2SO4 acidulation salt cake by-product, but the production of NaOH from sodium chloride yields chlorine. If the pulp manufacturer elects to buy only the NaOH and not the chlorine, a premium price is paid for the NaOH since the producer of the NaOH and chlorine must then sell or dispose of the chlorine himself. In essence, the papermaker is paying both for the caustic soda and the chlorine, even though he does not use the chlorine.
- crude tall oil can be prepared by the direct electrolysis of tall oil soap.
- a process for preparing crude tall oil from tall oil soap characterised in that it comprises the steps of: directly electrolyzing an aqueous tall oil soap solution under conditions of temperature, current density and time effective to form a dispersion of crude tall oil in an aqueous salt solution, and a caustic solution; and recovering said crude tall oil from said dispersion is provided.
- a dilute aqueous tall oil soap solution is placed in contact with an anode positioned within an anode chamber.
- the anode chamber is separated by a membrane (which preferably is chemically inert to the tall oil soap solution, permeable to sodium ions and impermeable to hydroxide ions) from a cathode chamber containing an aqueous electrolyte solution and having a cathode positioned therein.
- a current having a current density which is effective to electrolyze the water in both the anode and cathode chambers is applied to the anode and cathode.
- the electrolysis of the water in the anode chamber liberates protons which react with the tall oil soap to form crude tall oil and free sodium ions, which sodium ions migrate through the membrane to the cathode chamber.
- the sodium ions and the hydroxide ions formed by the electrolysis of the water in the cathode chamber then form a NaOH solution.
- the current is applied to the electrode for a time sufficient to substantially convert the tall oil soap to the crude tall oil.
- the crude tall oil is separated then from the anolyte, which anolyte comprises crude tall oil, water, sodium salts and lignin.
- the tall oil soap solution may be pre-treated prior to electrolysis to remove ions, such as calcium, and solids, such as sodium lignate, which may reduce the efficiency of the electrolysis.
- the NaOH may be recycled to the kraft pulping process as a chemical make-up for the loss of soda therein.
- Figure 1 is a schematic flow diagram of kraft pulping and crude tall oil recovery systems utilizing the present invention.
- Figure 2 is a diagrammatic representation of a batch process embodiment of the present invention.
- Figure 3 is a diagrammatic representation of a continuous process embodiment of the present invention.
- Resin acids are monocarboxylic diterpene acids commonly having the molecular formula C20H30O2.
- resin acids present are abietic, levopimaric, neoabietic, palustric, dehydroabietic, isopimaric, sandaracopimaric, pimaric, and secodehydroabietic acid.
- the fatty acids found in the coniferous woods are typically C16-C18 saturated or unsaturated fatty acids, including palmitic, stearic, palmitoleic, oleic and linoleic.
- Lignin is a phenylpropane polymer of amorphous structure which acts more or less as a plastic binder for the holocellulose fibers.
- wood chips 10 containing the resin acids, long-chain fatty acids, and lignin, and cooking liquor 12 comprising NaOH and Na2S are added to a digester and heated according to a predetermined schedule of temperature and time to dissolve a significant portion of the lignin in the cooking liquor.
- the fatty acid glycerides and the resin acids are saponified by the alkaline cooking liquor, thereby forming sodium salts of those acids.
- the resulting salts commonly referred to as "black liquor soap” or "tall oil soap" are dissolved in the cooking liquor along with sodium lignate.
- the cooked pulp and cooking liquor (collectively 14) are passed to a brown stock filter/washer, where the cooked pulp 16 is separated from the residual cooking liquor 18 and carried forward to the papermaking machine for processing into various grades of paper.
- the spent black liquor 20 is concentrated in a series of evaporators and placed in a strong black liquor storage facility.
- the strong black liquor is forwarded to the recovery furnace wherein the organic portion is burned to produce heat to raise steam, and the inorganic chemicals are reconstituted to form fresh pulp cooking liquors.
- the tall oil soap 22 is acidulated in an electrolytic cell to form a stream 24 of a dispersion of crude tall oil and lignin in aqueous sodium salt solution, and an aqueous NaOH solution 26.
- the NaOH 26 may be recycled to the kraft pulping process as a make-up chemical for lost sodium.
- the crude tall oil 28 is separated then from the solution 24 by methods discussed herein.
- the tall oil soap solution derived from the kraft pulping process is a high viscosity, gelatinous material which contains occluded black liquor with dissolved sodium lignate, and some calcium ions. It is believed that the presence of the calcium ions may reduce the sodium ion permeability of the membrane contained within the electrolytic cell upon extended use in the process of the present invention, while the presence of the sodium lignate may lead to membrane fouling. Therefore, the tall oil soap optionally may be pre-treated prior to the electrolysis of the soap to remove those calcium ions and sodium lignate, thus improving the efficiency of the electrolysis procedure.
- the viscosity of the aqueous tall oil soap solution should be sufficiently low to allow circulation of the tall oil soap solution through the electrolytic cell.
- One method of reducing the viscosity to a sufficiently low value is to dilute the tall oil soap with additional water.
- the inclusion of additional water in the tall oil soap solution requires handling of additional volumes of material in subsequent steps of the process and preferably is minimized.
- the temperature of the tall oil soap solution is adjusted to achieve the sufficiently low viscosity required to circulate the tall oil soap solution through the electrolytic cell.
- the temperature of the aqueous tall oil soap solution is less than 100°C, and more preferably between about 50°C and 80°C.
- the electrolysis of the tall oil soap to crude tall oil may be carried out either in a batch process or a continuous process.
- a diagram of a batch process embodiment of the present invention is presented.
- the aqueous tall oil soap solution 22 having a pH of 10-12 is placed in an appropriate first holding vessel 30.
- the tall oil soap solution is circulated through an anode chamber 32 and contacted with an anode 34 positioned therein.
- the anode chamber 32 is separated by a membrane 36 from a cathode chamber 38 having a cathode 40 positioned therein.
- the membrane 36 must be chemically inert with respect to the tall oil soap, and it must be permeable to free sodium ions, yet impermeable to hydroxide ions.
- an appropriate membrane is a Nafion® membrane (E.I. DuPont DeNemours & Co., Inc.).
- the current is applied to the anode and cathode for a time sufficient to substantially convert the tall oil soap to crude tall oil.
- the conversion of the tall oil soap to crude tall oil may be monitored by the pH of the anolyte.
- the electrolysis of the tall oil soap may be terminated when the pH of the anolyte is reduced to less than about 4, and more preferably about 3.
- Sodium ions migrating through the membrane form additional aqueous NaOH in the cathode compartment 38 and accumulate in tank 42.
- Molecular oxygen 44 and hydrogen 46 gases are produced as by-products of the electrolysis at the anode and cathode, respectively.
- FIG. 3 a diagram of a multistage, continuous process embodiment of the present invention is shown.
- the tall oil soap 22 is added to a tall oil soap feed mixture 48 and circulated through a first anode chamber 50 having a first anode 52 positioned therein.
- the first anode chamber 50 is separated by a first membrane 54 from a first cathode chamber 58 having a first cathode 56 positioned therein.
- An aqueous NaOH solution 26 having a concentration of from about 0.1-5 M is circulated through the first cathode chamber 58 and contacted with the first cathode 56.
- a first anolyte 60 comprising protons, free sodium ions, tall oil soap, and crude tall oil, and a first catholyte 62 comprising NaOH (0.1-5 M), preferably of greater concentration than the NaOH solution 26, are produced.
- the partially electrolyzed anolyte 60 is circulated through a second anode chamber 70 having a second anode 72 positioned therein.
- the second anode chamber 70 is separated by a second membrane 74 from a second cathode chamber 78 having a second cathode 76 positioned therein.
- the first catholyte 62 is circulated through the second cathode chamber 78 and contacted with the second cathode 76, thereby producing a second catholyte 64 having a NaOH concentration between about 0.1-5 M and preferably greater than the first catholyte 62.
- O2 44 and H2 46 gases are produced by the electrolysis.
- the second anolyte 80 may be electrolyzed to the extent that the conversion of the tall oil soap to the crude tall oil is substantially complete, in which case the fully electrolyzed anolyte 82 would be transported to the crude tall oil recovery system, such as a decanter 84 as shown.
- the fully electrolyzed anolyte 82 is allowed to separate into a lower aqueous phase 86 containing sodium salts such as sodium sulfate, and an upper phase 88 consisting essentially of crude tall oil.
- the crude tall oil 88 is removed for further processing to produce tall oil fatty acids and tall oil rosins.
- the aqueous phase 86 optionally may be recycled and combined with the tall oil soap 22 in addition to make-up water 68 to form the tall oil soap feed mixture 48. If the anolyte 80 were further electrolyzed, but not completely electrolyzed, the partially electrolyzed second anolyte 80 would be transported to a third anode chamber (not shown) and further electrolyzed as described above.
- caustic soda 66 recovered as NaOH may be recycled to the kraft pulping process as a make-up chemical.
- a current having a current density sufficiently high to electrolyze the water in both the anode and cathode chambers is applied to the anode and cathode.
- current density represents the current (kA) divided by the electrode surface area (m2).
- Power consumption per unit of NaOH in an electrolytic process is directly proportional to the cell potential and inversely proportional to the current efficiency.
- the primary electrolytic reaction is the splitting of water to H2 and O2, which is well understood and highly efficient.
- the assumption of 99% current efficiency is consistent with the present state of the art of the membrane.
- the process operating potential is more variable and is highly dependent upon cell and process design.
- the minimization of the cell potential, while still maintaining adequate electrolysis to acidify the tall oil soap is desired.
- the cell potential also referred to as cell voltage, is influenced by a number of factors, and is normally treated as the sum of reaction EMF or thermodynamic equilibrium potential, electrode polarization and ohmic polarization or resistivity.
- thermodynamic equilibrium voltage is a function of the reactant and product concentrations.
- the only factors which could change significantly over the course of the electrolysis are the concentrations of protons in the anolyte and the hydroxide ions in the catholyte. As these reaction products build up, the cell EMF gradually rises. Product and reactant concentrations can vary by several orders of magnitude before they significantly change the equilibrium potential, and therefore are not a major factor in the cell potential.
- Electrode polarization arises at high current densities where the rate of reaction is greater than the rate of species transport to or from the electrode surface. For example, hydroxide ions are formed at the cathode surface. These ions then diffuse through a laminar boundary layer into the bulk of the catholyte. If the rate of hydroxide production is rapid, the ionic concentration at the electrode surface increases, causing an increase in the potential needed to effect a reduction. Electropolarization can be minimized by slowing the rate of reaction (i.e., operating at low current density), or by enhancing the rate of mass transport with good cell design, agitation or electrolyte circulation.
- Ohmic polarization is the voltage required to pass current through the resistive electrolyte solution.
- the ohmic potential is minimized by the use of low current densities, close electrode spacing and high specific conductivities.
- Cell potential is also a function of the conductivity of the electrolyte. If ohmic polarization is determined to make up a significant fraction of the cell potential, co-electrolytes which will increase conductivity without affecting current efficiency may be used.
- the tall oil soap to be electrolyzed will contain from about 0.1-1.5 M Na2SO4.
- the current density of the present invention ranges from about 0.5 to about 5 kA/m2, more preferably from about 1 to 3 kA/m2.
- the cell potential utilized in the present invention is from about 2 to 12 volts, more preferably from about 2 to 8 volts. Most preferably the cell potential of the present invention ranges from about 5 to 7 volts.
- the net reaction is a two electron process: 2RCOO ⁇ Na+ + 3H2O ---> 2RCOOH + 2Na+OH ⁇ + 1/2 O 2(g) + H 2(g) (5)
- the crude tall oil must be recovered from the electrolyzed anolyte for further processing.
- techniques which may be used are distillation, sedimentation followed by decantation, or centrifugation. If dilution of the tall oil soap with water beyond 1:1 is necessary, the recovery of the crude tall oil will require handling larger volumes of residual liquid. Therefore, it is preferable that the dilution of the tall oil soap with additional water prior to the electrolysis be minimized.
- Direct electrolysis of tall oil soap to crude tall oil has one significant advantage over the H2SO4 acidulation process in that sodium is recovered as NaOH.
- the NaOH has high value in the paper mills as a chemical make-up in the kraft pulping process. Therefore, the most preferred embodiment of the present invention recycles the NaOH from the electrolysis process to the kraft pulping process.
- the use of a Nafion® membrane permits sufficient water to pass from the anode compartment into the cathode compartment such that aqueous caustic soda at 12-20% NaOH accumulates. This is sufficiently concentrated that it may usefully be recirculated for use in the pulp mill without the need for further evaporative concentration stages.
- the present invention then satisfies a long felt need in the papermaking industry in that it surprisingly provides a method for the production of crude tall oil from tall oil soap without the production of Na2SO4 salt cake, the disposal of which cake is becoming more and more of a serious problem in the papermaking industry.
- the invention eliminates both the problems of the crude tall oil producers losing the credit value for the cake, which heretofore has been returned to the pulp mill, and disposal of the cake once the pulp mill no longer will accept the cake.
- the present invention provides an economically and environmentally sound process for the production of valuable NaOH for use as a make-up chemical in the kraft pulping process, without the problems associated with the prior art methods which generate chlorine.
- An electrolytic cell having an electrode area of about 50 cm2 was constructed according to Figure 2.
- About 400 grams of the tall oil soap were added to the holding vessel and diluted to about 2 liters with water containing about 75 grams of Na2SO4.
- the electrolysis was terminated when the pH of the anolyte dropped from about 10 to about 3, while the cell potential dropped from about 12 to about 5 volts as the conductivity of the solutions increased.
- the resulting crude tall oil was decanted from the anolyte after gravity separation.
- the crude tall oil was analyzed and found to have a soap number of zero, indicating that the conversion of the tall oil soap to the crude tall oil was substantially completed.
- NaOH aqueous sodium hydroxide solution
- the initial cell potential of 15 volts increased after approximately 35 minutes to about 20 volts and subsequently decreased at the end of 1 hour to about 7 volts, at which point it remained essentially constant throughout the remaining 1 hour and 20 minutes.
- the electrolysis was terminated when the pH of the anolyte dropped from about 10 to about 3.
- the resulting crude tall oil was decanted from the anolyte after gravity separation.
- the crude tall oil was analyzed and found to have a soap number of 0, indicating that the conversion of the tall oil soap to the crude tall oil was substantially completed.
- the cathode chamber contained approximately 360 grams of a 2.5 M sodium hydroxide solution, indicating a recovery of about 0.7 M of sodium hydroxide or about 17 grams of sodium.
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Abstract
Description
- The present invention relates to the direct conversion of tall oil soap to tall oil.
- Coniferous woods, especially pine, contain among other components, lignin, resin acids and long-chain fatty acids. Crude tall oil, a mixture of the resin and fatty acids, is produced as a chemical by-product of the kraft pulping process.
- In the kraft pulping process, wood chips are fed into a digester and a "white" cooking liquor containing sodium hydroxide (NaOH) and sodium sulfide (Na₂S) is added. The contents are then heated according to a predetermined schedule to complete the cooking reactions, wherein the resin acids and fatty acids are released from the wood chips and saponified. The resulting cooked pulp is separated from the residual cooking liquor, known as black liquor, in a brown stock washing process. The sodium salts of the resin acids and fatty acids, commonly referred to as tall oil soap or "black liquor soap", are suspended in the black liquor. The wood pulp is treated further in the papermaking process to produce papers of various grades.
- The recovery of chemicals from the black liquor, the reconstitution of those chemicals to form fresh cooking liquors, the realization of energy from incineration of organic residuals, and minimization of air and water pollution, are all vital parts of the kraft process. Among those chemicals which are recovered from the black liquor is tall oil soap. The soap is contained in the "weak" black liquor (i.e. unconcentrated) which is recovered in the pulping process as a filtrate from the pulp separation.
- The initial weak black liquor (at about 15% solids) is filtered to remove fiber and is passed into a weak liquor skimmer. Thirty per cent (30%) to 70% of the available black liquor soap is skimmed off. The black liquor then passes through several stages of evaporative concentration to raise the solids content to 25-30%. The black liquor then passes through a second skimmer from which the remaining 30-70% of soap is skimmed off. The black liquor finally passes through more stages of evaporative concentration to raise the solids to 50-60%. It is then fed to a recovery furnace to be burned. Burning the organic content of the black liquor provides energy for the paper making process and reconstitutes the inorganic chemicals for reuse in fresh pulping liquors (Foran, C. D., "Black Liquor Soap Recovery Methods Employed by Union Camp," Naval Stores Review, 94, 14 (1984)).
- One skilled in the art of making kraft paper will recognize that there are various techniques for recovering tall oil soap from the kraft black liquor. Frequently, black liquor soap is degassed (or concentrated) to remove foam and is then settled to decant out excess residual black liquor.
- The separated tall oil soap is then normally acidulated with sulfuric acid to form crude tall oil, which can be refined by vacuum fractionation to form tall oil fatty acids and tall oil rosin. The fatty acids and rosin are used in numerous industrial applications, including the preparation of polyamides, rosin resins, adhesive and epoxy compositions. Heretofore the acidulation process comprised the addition of sulfuric acid (H₂SO₄) to the tall oil soap to produce crude tall oil and Na₂SO₄ salt cake solution. One skilled in the art will recognize that there are various acidulation processes utilizing H₂SO₄ for the conversion of tall oil soap to crude tall oil. For a more thorough discussion with references, see McSweeney, E. E.; "Sulfate Naval Stores", Naval Stores 171, (1989). The Na₂SO₄ as described above is recycled to the kraft pulping process to make up for sodium and sulfur losses.
- The economics of the production of crude tall oil from tall oil soap depends to a considerable degree on the ability to dispose of the spent acid from the acidulation process. Heretofore, the producers of crude tall oil would sell the by-product Na₂SO₄, hereinafter referred to as salt cake, to the paper mills as make-up chemicals in the kraft pulping process. A typical kraft mill in the early '70s was designed for cost effective chemical recovery with little regard for the environment. Sodium recovery was around 93% while sulfur recovery was only about 61% (Twiss, A.H., Naval Stores Review, 94 (2), 14 (1984)). With the introduction of more stringent environmental controls on the emission of air and water pollutants, a state of the art greenfield mill (1984) being designed to meet the more stringent new source performance standards was predicted to achieve over 97% sodium recovery and 91% sulfur recovery. Twiss reports that as of 1984, total sodium loss expressed as equivalent salt cake had been decreased from 67.5 to 35 kg/t (135 to 70 pounds/ton) of pulp for a mill meeting then existing source standards, down to 26.5 kg/t (53 pounds/ton) for a new state of the art (1984) mill. Total sulfur losses were decreased from 87.5, to 37.5, to 20 kg of equivalent salt cake per tonne of pulp (from 175, to 75, to 40 pounds of equivalent salt cake per ton of pulp), due mainly to reduced emissions from the recovery boiler and lime kiln. These reduced losses have had a drastic impact on the make-up sodium and sulfur requirements in the kraft pulping process, which must balance the losses. The result is that the paper mills no longer desire or require the previous levels of salt cake produced in the sulfuric acid acidulation of tall oil soap to make-up for losses of sodium and sulfur. In fact, a large amount of the salt cake make-up has been replaced with more costly caustic soda to lower the sulfur make-up. Without the paper mills to use the salt cake produced by the acidulation of tall oil soap, it would appear that the salt cake must be sewered. Organic contaminants contained in the sewer discharge which contains the salt cake increases the biochemical oxygen demand (BOD) levels in the water streams receiving the discharge. Therefore, the limitations on sewering of the salt cake will increase due to even more stringent environmental restrictions.
- Wong, also discussed tall oil soap acidulation and sulfur balance problems in kraft mills (Wong, A., Naval Stores Review, 94, (3), 8 (1984)). Wong reported the same problems associated with the salt cake from the acidulation of the tall oil soap as did Twiss. Wong proposed the replacement of H₂SO₄ used in soap acidulation with chlorine dioxide generator effluent to lower the sulfur input into the mill liquor system. However, the reduced sulfur input would still be higher than the losses in the mill by about 10%.
- It has been suggested that the tall oil acidulation process can be modified to reduce or eliminate by-product sulfur by the use of other common acids, such as hydrochloric. The use of such acids, however, would prohibit recovery of the spent acid due to build-up of extraneous anions and problems in tall oil purification. Electrolysis of spent acid to NaOH and a mixture of H₂SO₄ and Na₂SO₄ has also been investigated. Replacement of about one-half of the H₂SO₄ with carbon dioxide has also been patented by Bills, A. M., U. S.-A-3,901,869.
- These proposed solutions only partially address the problem. Very simply, too much sulfur as Na₂SO₄ is produced in the soap acidulation plants to be recycled to the paper mill liquor system for satisfactory sulfidity and sulfur emissions control.
- Another problem associated with the reduced requirement for Na₂SO₄ salt cake as a make-up chemical in the kraft pulping process is that caustic soda must be used to replace sodium lost in the kraft pulping process. Not only is the caustic soda more expensive than the H₂SO₄ acidulation salt cake by-product, but the production of NaOH from sodium chloride yields chlorine. If the pulp manufacturer elects to buy only the NaOH and not the chlorine, a premium price is paid for the NaOH since the producer of the NaOH and chlorine must then sell or dispose of the chlorine himself. In essence, the papermaker is paying both for the caustic soda and the chlorine, even though he does not use the chlorine.
- There is a long felt need in the papermaking industry for a process to acidulate tall oil soap to form crude tall oil without the formation of Na₂SO₄ salt cake. There is also a need to economically produce caustic soda to be recycled to the pulping process without the production of chlorine. These needs have not been satisfied to date, even in the face of more stringent environmental emission controls and reduced requirements for salt cake in the paper mills.
- Therefore it is an object of the present invention to provide a process for the acidulation of tall oil soap to form crude tall oil without the formation of Na₂SO₄ salt cake. It is another object of the present invention to provide a process for the economical production of caustic soda to be recycled to the kraft pulping process without the production of chlorine.
- It has been discovered in accordance with the present invention that crude tall oil can be prepared by the direct electrolysis of tall oil soap.
- According to the invention a process for preparing crude tall oil from tall oil soap, characterised in that it comprises the steps of:
directly electrolyzing an aqueous tall oil soap solution under conditions of temperature, current density and time effective to form a dispersion of crude tall oil in an aqueous salt solution, and a caustic solution; and
recovering said crude tall oil from said dispersion is provided. - In a preferred embodiment of the invention, a dilute aqueous tall oil soap solution is placed in contact with an anode positioned within an anode chamber. The anode chamber is separated by a membrane (which preferably is chemically inert to the tall oil soap solution, permeable to sodium ions and impermeable to hydroxide ions) from a cathode chamber containing an aqueous electrolyte solution and having a cathode positioned therein. A current having a current density which is effective to electrolyze the water in both the anode and cathode chambers is applied to the anode and cathode. The electrolysis of the water in the anode chamber liberates protons which react with the tall oil soap to form crude tall oil and free sodium ions, which sodium ions migrate through the membrane to the cathode chamber. The sodium ions and the hydroxide ions formed by the electrolysis of the water in the cathode chamber then form a NaOH solution. The current is applied to the electrode for a time sufficient to substantially convert the tall oil soap to the crude tall oil. The crude tall oil is separated then from the anolyte, which anolyte comprises crude tall oil, water, sodium salts and lignin.
- Optionally, the tall oil soap solution may be pre-treated prior to electrolysis to remove ions, such as calcium, and solids, such as sodium lignate, which may reduce the efficiency of the electrolysis. Also optionally, the NaOH may be recycled to the kraft pulping process as a chemical make-up for the loss of soda therein.
- Figure 1 is a schematic flow diagram of kraft pulping and crude tall oil recovery systems utilizing the present invention.
- Figure 2 is a diagrammatic representation of a batch process embodiment of the present invention.
- Figure 3 is a diagrammatic representation of a continuous process embodiment of the present invention.
- Coniferous wood, particularly pine, contains resin acids in the free acid form, long-chain fatty acids primarily in the form of glycerides, and lignin. Resin acids are monocarboxylic diterpene acids commonly having the molecular formula C₂₀H₃₀O₂. Among those resin acids present are abietic, levopimaric, neoabietic, palustric, dehydroabietic, isopimaric, sandaracopimaric, pimaric, and secodehydroabietic acid. The fatty acids found in the coniferous woods are typically C₁₆-C₁₈ saturated or unsaturated fatty acids, including palmitic, stearic, palmitoleic, oleic and linoleic. Lignin is a phenylpropane polymer of amorphous structure which acts more or less as a plastic binder for the holocellulose fibers.
- Referring to Figure 1, in a kraft pulping process,
wood chips 10 containing the resin acids, long-chain fatty acids, and lignin, and cooking liquor 12 comprising NaOH and Na₂S are added to a digester and heated according to a predetermined schedule of temperature and time to dissolve a significant portion of the lignin in the cooking liquor. During the cooking process, the fatty acid glycerides and the resin acids are saponified by the alkaline cooking liquor, thereby forming sodium salts of those acids. The resulting salts, commonly referred to as "black liquor soap" or "tall oil soap", are dissolved in the cooking liquor along with sodium lignate. - The cooked pulp and cooking liquor (collectively 14) are passed to a brown stock filter/washer, where the cooked
pulp 16 is separated from theresidual cooking liquor 18 and carried forward to the papermaking machine for processing into various grades of paper. Theresidual cooking liquor 18, known as "black liquor", which contains dissolved tall oil soap and lignin, is placed in a weak black liquor storage facility wherein the tall oil soap is separated from the black liquor by methods discussed previously herein. The spentblack liquor 20 is concentrated in a series of evaporators and placed in a strong black liquor storage facility. The strong black liquor is forwarded to the recovery furnace wherein the organic portion is burned to produce heat to raise steam, and the inorganic chemicals are reconstituted to form fresh pulp cooking liquors. - According to an embodiment of the process of the present invention, the
tall oil soap 22 is acidulated in an electrolytic cell to form astream 24 of a dispersion of crude tall oil and lignin in aqueous sodium salt solution, and anaqueous NaOH solution 26. Optionally, theNaOH 26 may be recycled to the kraft pulping process as a make-up chemical for lost sodium. The crudetall oil 28 is separated then from thesolution 24 by methods discussed herein. - The tall oil soap solution derived from the kraft pulping process is a high viscosity, gelatinous material which contains occluded black liquor with dissolved sodium lignate, and some calcium ions. It is believed that the presence of the calcium ions may reduce the sodium ion permeability of the membrane contained within the electrolytic cell upon extended use in the process of the present invention, while the presence of the sodium lignate may lead to membrane fouling. Therefore, the tall oil soap optionally may be pre-treated prior to the electrolysis of the soap to remove those calcium ions and sodium lignate, thus improving the efficiency of the electrolysis procedure.
- Prior to electrolysis, the viscosity of the aqueous tall oil soap solution should be sufficiently low to allow circulation of the tall oil soap solution through the electrolytic cell. One method of reducing the viscosity to a sufficiently low value is to dilute the tall oil soap with additional water. However, the inclusion of additional water in the tall oil soap solution requires handling of additional volumes of material in subsequent steps of the process and preferably is minimized. More preferably, the temperature of the tall oil soap solution is adjusted to achieve the sufficiently low viscosity required to circulate the tall oil soap solution through the electrolytic cell. Preferably the temperature of the aqueous tall oil soap solution is less than 100°C, and more preferably between about 50°C and 80°C.
- The electrolysis of the tall oil soap to crude tall oil may be carried out either in a batch process or a continuous process. Referring to Figure 2, a diagram of a batch process embodiment of the present invention is presented. The aqueous tall
oil soap solution 22 having a pH of 10-12 is placed in an appropriate first holdingvessel 30. The tall oil soap solution is circulated through ananode chamber 32 and contacted with ananode 34 positioned therein. Theanode chamber 32 is separated by amembrane 36 from acathode chamber 38 having acathode 40 positioned therein. Themembrane 36 must be chemically inert with respect to the tall oil soap, and it must be permeable to free sodium ions, yet impermeable to hydroxide ions. One example of an appropriate membrane is a Nafion® membrane (E.I. DuPont DeNemours & Co., Inc.). - An aqueous
sodium hydroxide solution 26 contained in asecond holding vessel 42 and having a concentration ranging from about 0.1-5 M, more preferably from about 0.5-2.5 M, is circulated through thecathode chamber 38 and contacted with thecathode 40. The current is applied to the anode and cathode for a time sufficient to substantially convert the tall oil soap to crude tall oil. The conversion of the tall oil soap to crude tall oil may be monitored by the pH of the anolyte. The electrolysis of the tall oil soap may be terminated when the pH of the anolyte is reduced to less than about 4, and more preferably about 3. Sodium ions migrating through the membrane form additional aqueous NaOH in thecathode compartment 38 and accumulate intank 42.Molecular oxygen 44 andhydrogen 46 gases are produced as by-products of the electrolysis at the anode and cathode, respectively. - Referring to Figure 3, a diagram of a multistage, continuous process embodiment of the present invention is shown. The
tall oil soap 22 is added to a tall oilsoap feed mixture 48 and circulated through afirst anode chamber 50 having afirst anode 52 positioned therein. Thefirst anode chamber 50 is separated by afirst membrane 54 from afirst cathode chamber 58 having afirst cathode 56 positioned therein. Anaqueous NaOH solution 26 having a concentration of from about 0.1-5 M is circulated through thefirst cathode chamber 58 and contacted with thefirst cathode 56. Upon partial electrolysis of the tall oil soap solution, afirst anolyte 60 comprising protons, free sodium ions, tall oil soap, and crude tall oil, and afirst catholyte 62 comprising NaOH (0.1-5 M), preferably of greater concentration than theNaOH solution 26, are produced. The partially electrolyzedanolyte 60 is circulated through asecond anode chamber 70 having a second anode 72 positioned therein. Thesecond anode chamber 70 is separated by asecond membrane 74 from asecond cathode chamber 78 having asecond cathode 76 positioned therein. Thefirst catholyte 62 is circulated through thesecond cathode chamber 78 and contacted with thesecond cathode 76, thereby producing asecond catholyte 64 having a NaOH concentration between about 0.1-5 M and preferably greater than thefirst catholyte 62. Again,O₂ 44 andH₂ 46 gases are produced by the electrolysis. - The
second anolyte 80 may be electrolyzed to the extent that the conversion of the tall oil soap to the crude tall oil is substantially complete, in which case the fully electrolyzedanolyte 82 would be transported to the crude tall oil recovery system, such as adecanter 84 as shown. In thedecanter 84, the fully electrolyzedanolyte 82 is allowed to separate into a loweraqueous phase 86 containing sodium salts such as sodium sulfate, and anupper phase 88 consisting essentially of crude tall oil. The crudetall oil 88 is removed for further processing to produce tall oil fatty acids and tall oil rosins. Theaqueous phase 86 optionally may be recycled and combined with thetall oil soap 22 in addition to make-upwater 68 to form the tall oilsoap feed mixture 48. If theanolyte 80 were further electrolyzed, but not completely electrolyzed, the partially electrolyzedsecond anolyte 80 would be transported to a third anode chamber (not shown) and further electrolyzed as described above. Optionally,caustic soda 66 recovered as NaOH may be recycled to the kraft pulping process as a make-up chemical. - It will be recognized by one of ordinary skill in the art that the number and design of the electrolytic cells will be determined by various factors, and the embodiments previously discussed is by no means intended to limit the scope and spirit of the present invention.
- A current having a current density sufficiently high to electrolyze the water in both the anode and cathode chambers is applied to the anode and cathode. One of ordinary skill in the art will recognize that the proper current density is determined by a number of factors including the surface area of the electrodes, electrode spacing, design of the electrode chambers, resistance of the electrolytes, and the like. As used herein, current density represents the current (kA) divided by the electrode surface area (m²).
- Power consumption per unit of NaOH in an electrolytic process is directly proportional to the cell potential and inversely proportional to the current efficiency. In this process, the primary electrolytic reaction is the splitting of water to H₂ and O₂, which is well understood and highly efficient. The assumption of 99% current efficiency is consistent with the present state of the art of the membrane. The process operating potential is more variable and is highly dependent upon cell and process design. The minimization of the cell potential, while still maintaining adequate electrolysis to acidify the tall oil soap is desired. The cell potential, also referred to as cell voltage, is influenced by a number of factors, and is normally treated as the sum of reaction EMF or thermodynamic equilibrium potential, electrode polarization and ohmic polarization or resistivity.
- The thermodynamic equilibrium voltage is a function of the reactant and product concentrations. The only factors which could change significantly over the course of the electrolysis are the concentrations of protons in the anolyte and the hydroxide ions in the catholyte. As these reaction products build up, the cell EMF gradually rises. Product and reactant concentrations can vary by several orders of magnitude before they significantly change the equilibrium potential, and therefore are not a major factor in the cell potential.
- Electrode polarization arises at high current densities where the rate of reaction is greater than the rate of species transport to or from the electrode surface. For example, hydroxide ions are formed at the cathode surface. These ions then diffuse through a laminar boundary layer into the bulk of the catholyte. If the rate of hydroxide production is rapid, the ionic concentration at the electrode surface increases, causing an increase in the potential needed to effect a reduction. Electropolarization can be minimized by slowing the rate of reaction (i.e., operating at low current density), or by enhancing the rate of mass transport with good cell design, agitation or electrolyte circulation.
- Ohmic polarization is the voltage required to pass current through the resistive electrolyte solution. The ohmic potential is minimized by the use of low current densities, close electrode spacing and high specific conductivities.
- Higher current densities reduce capital cost by reducing electrode size, but increase power consumption by raising the voltage drop due to electrode and ohmic polarization. Therefore it is preferable to optimally minimize the current density to avoid these potential problems. Cell potential is also a function of the conductivity of the electrolyte. If ohmic polarization is determined to make up a significant fraction of the cell potential, co-electrolytes which will increase conductivity without affecting current efficiency may be used. Preferably, the tall oil soap to be electrolyzed will contain from about 0.1-1.5 M Na₂SO₄.
- The current density of the present invention ranges from about 0.5 to about 5 kA/m², more preferably from about 1 to 3 kA/m². The cell potential utilized in the present invention is from about 2 to 12 volts, more preferably from about 2 to 8 volts. Most preferably the cell potential of the present invention ranges from about 5 to 7 volts.
-
- The free sodium ions generated in the anode chamber then migrate through the membrane to the cathode chamber. At the cathode, water is split and the protons are reduced to hydrogen gas, releasing free hydroxide ions:
2H₂O + 2e⁻ ----> H2(g) + 2OH⁻ E°= -0.83v (4)
Charge neutrality is maintained by the flow of electrons through the external electrical circuit and by migration of the sodium ions from the anolyte to the catholyte across the membrane. The net reaction is a two electron process:
2RCOO⁻Na⁺ + 3H₂O ---> 2RCOOH + 2Na⁺OH⁻ + 1/2 O2(g) + H2(g) (5)
After the acidulation of the tall oil soap is complete, the crude tall oil must be recovered from the electrolyzed anolyte for further processing. Among techniques which may be used are distillation, sedimentation followed by decantation, or centrifugation. If dilution of the tall oil soap with water beyond 1:1 is necessary, the recovery of the crude tall oil will require handling larger volumes of residual liquid. Therefore, it is preferable that the dilution of the tall oil soap with additional water prior to the electrolysis be minimized. - Direct electrolysis of tall oil soap to crude tall oil has one significant advantage over the H₂SO₄ acidulation process in that sodium is recovered as NaOH. The NaOH has high value in the paper mills as a chemical make-up in the kraft pulping process. Therefore, the most preferred embodiment of the present invention recycles the NaOH from the electrolysis process to the kraft pulping process. The use of a Nafion® membrane permits sufficient water to pass from the anode compartment into the cathode compartment such that aqueous caustic soda at 12-20% NaOH accumulates. This is sufficiently concentrated that it may usefully be recirculated for use in the pulp mill without the need for further evaporative concentration stages.
- The present invention then satisfies a long felt need in the papermaking industry in that it surprisingly provides a method for the production of crude tall oil from tall oil soap without the production of Na₂SO₄ salt cake, the disposal of which cake is becoming more and more of a serious problem in the papermaking industry. The invention eliminates both the problems of the crude tall oil producers losing the credit value for the cake, which heretofore has been returned to the pulp mill, and disposal of the cake once the pulp mill no longer will accept the cake. Additionally, the present invention provides an economically and environmentally sound process for the production of valuable NaOH for use as a make-up chemical in the kraft pulping process, without the problems associated with the prior art methods which generate chlorine.
- An electrolytic cell having an electrode area of about 50 cm² was constructed according to Figure 2. About 400 grams of the tall oil soap were added to the holding vessel and diluted to about 2 liters with water containing about 75 grams of Na₂SO₄. The aqueous tall oil soap solution was circulated at a rate of 1 liter per minute through the anode chamber and a current of 10 amps (current density = 2 kA/m²) was applied to the electrodes for roughly two hours, followed by 20 amps (current density = 4 kA/m²) for 0.5 hours. The electrolysis was terminated when the pH of the anolyte dropped from about 10 to about 3, while the cell potential dropped from about 12 to about 5 volts as the conductivity of the solutions increased. The resulting crude tall oil was decanted from the anolyte after gravity separation. The crude tall oil was analyzed and found to have a soap number of zero, indicating that the conversion of the tall oil soap to the crude tall oil was substantially completed.
- Utilizing the electrolytic cell of Example 1, about 400 grams of the tall oil soap were added to the holding vessel. About 1600 grams of water containing about 75 grams of Na₂SO₄ were added to the holding vessel. The aqueous tall oil soap solution was circulated at a rate of one liter per minute through the anode chamber and a current of 10 amps (current density = 2 kA/m²) was applied to the electrodes for roughly 2 hours and 20 minutes. About 300 grams of a 0.5 M aqueous sodium hydroxide solution (NaOH) was added to a second holding vessel and circulated through a cathode chamber and contacted with the cathode positioned therein for the same 2 hour and 20 minute period. The initial cell potential of 15 volts increased after approximately 35 minutes to about 20 volts and subsequently decreased at the end of 1 hour to about 7 volts, at which point it remained essentially constant throughout the remaining 1 hour and 20 minutes. The electrolysis was terminated when the pH of the anolyte dropped from about 10 to about 3. The resulting crude tall oil was decanted from the anolyte after gravity separation. The crude tall oil was analyzed and found to have a soap number of 0, indicating that the conversion of the tall oil soap to the crude tall oil was substantially completed. Upon completion of the electrolysis, the cathode chamber contained approximately 360 grams of a 2.5 M sodium hydroxide solution, indicating a recovery of about 0.7 M of sodium hydroxide or about 17 grams of sodium.
Claims (15)
- A process for preparing crude tall oil from tall oil soap, characterised in that it comprises the steps of:
directly electrolyzing an aqueous tall oil soap solution under conditions of temperature, current density and time effective to form a dispersion of crude tall oil in an aqueous salt solution, and a caustic solution; and
recovering said crude tall oil from said dispersion. - A process as claimed in claim 1, wherein the electrolysis of the aqueous tall oil soap solution is effected by:
placing an aqueous tall oil soap solution in contact with an anode positioned within an anode chamber, said anode chamber being separated by a membrane from a cathode chamber containing an aqueous electrolyte solution and having a cathode positioned therein,
applying a current having a current density effective to electrolyze the water in said anode chamber and said cathode chamber to said anode and cathode, said current being applied for a time sufficient to substantially convert said tall oil soap to crude tall oil;
wherein the electrolysis of said water in said anode chamber causes the formation of said crude tall oil, protons and free sodium ions, which sodium ions migrate through said membrane to said cathode chamber, and wherein the electrolysis of said water in said cathode chamber causes the formation of hydroxide ions which in combination with said sodium ions constitute sodium hydroxide;
the said crude tall oil being recovered from the electrolysed tall oil soap solution. - The process of claim 2 wherein the viscosity of said aqueous tall oil soap solution is sufficiently low to allow circulation through said anode chamber.
- The process of claim 2 or claim 3 wherein said membrane is chemically inert to said tall oil soap solution, permeable to said free sodium ions and impermeable to said hydroxide ions.
- The process of any one of claims 2, 3 and 4 further comprising pre-treating said aqueous tall oil soap solution prior to said contact with said anode to substantially remove calcium ions and sodium lignate.
- The process of claim 5 wherein the pretreatment comprises precipitation and/or filtration.
- The process of any one of claims 2 to 6, wherein said tall oil soap solution is placed in contact with a plurality of anodes.
- The process of any preceding claim wherein said temperature is less than 100°C.
- The process of claim 8 wherein said temperature is between 50°C and 80°C.
- The process of any preceding claim wherein said current density is between 0.5 and 5 kA/m².
- The process of claim 10 wherein said current density is from 1-3 kA/m².
- The process of any preceding claim wherein the electrolysis is carried out for a time sufficient to lower the pH of the electrolyzed aqueous tall oil solution to less than about 4.
- The process of any preceding claim wherein the recovery of said crude tall oil comprises techniques selected from sedimentation, centrifugation and decantation.
- The process of any preceding claim further comprising recycling said caustic solution to a Kraft pulping process.
- The process of any preceding claim wherein the aqueous tall oil soap solution is a by-product of a Kraft pulping process.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/747,547 US5164480A (en) | 1991-08-20 | 1991-08-20 | Method for the manufacture of tall oils |
PCT/US1992/006390 WO1993003815A1 (en) | 1991-08-20 | 1992-08-03 | Method for the manufacture of tall oils |
US747547 | 1996-11-12 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0608244A4 EP0608244A4 (en) | 1994-06-14 |
EP0608244A1 EP0608244A1 (en) | 1994-08-03 |
EP0608244B1 true EP0608244B1 (en) | 1995-12-13 |
Family
ID=25005562
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP92917068A Expired - Lifetime EP0608244B1 (en) | 1991-08-20 | 1992-08-03 | Method for the manufacture of tall oils |
Country Status (8)
Country | Link |
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US (1) | US5164480A (en) |
EP (1) | EP0608244B1 (en) |
BR (1) | BR9206383A (en) |
CA (1) | CA2115762A1 (en) |
FI (1) | FI940773A (en) |
NZ (1) | NZ243711A (en) |
WO (1) | WO1993003815A1 (en) |
ZA (1) | ZA925463B (en) |
Families Citing this family (17)
Publication number | Priority date | Publication date | Assignee | Title |
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CA2192889C (en) * | 1995-12-15 | 2005-08-09 | Qingquan Su | Method and apparatus for separating oil from water in wastewater containing an emulsified oil |
FI961930A (en) * | 1996-05-07 | 1997-11-08 | Ahlstrom Machinery Oy | Process and apparatus for streamlining an alkaline process for the production of cellulose |
FI104491B (en) * | 1996-12-30 | 2000-02-15 | Aga Ab | Method and apparatus for purifying a crude tall oil filter |
ATE362506T1 (en) * | 2004-09-21 | 2007-06-15 | Linde Ag | METHOD FOR OBTAINING TALL OIL OR TALL OIL FUEL |
US8580139B2 (en) * | 2008-08-02 | 2013-11-12 | Georgia-Pacific Chemicals Llc | Dedusting compositions and methods for making and using same |
CN102112574B (en) | 2008-08-02 | 2014-07-02 | 佐治亚-太平洋化工品有限公司 | Pitch emulsions |
US8317994B2 (en) * | 2008-08-07 | 2012-11-27 | Westlake Vinyl Corporation | Method of concentrating an aqueous caustic alkali using a catholyte heat recovery evaporator |
WO2011028964A1 (en) | 2009-09-02 | 2011-03-10 | Georgia-Pacific Chemicals Llc | Dedusting agents for fiberglass products and methods for making and using same |
WO2011028940A1 (en) | 2009-09-02 | 2011-03-10 | Georgia-Pacific Chemicals Llc | Dedusting compositions and methods for making and using same |
ES2488216T3 (en) | 2010-04-16 | 2014-08-26 | Arizona Chemical Company, Llc | Tire rubber comprising pine oil pitch |
CA2806914C (en) | 2010-09-10 | 2015-04-21 | Arizona Chemical Company, Llc | Method for producing crude tall oil by soap washing with calcium carbonate removal |
US10227460B2 (en) | 2014-08-07 | 2019-03-12 | Georgia-Pacific Chemicals Llc | Lignocellulose composite products |
GB2563151B (en) | 2017-09-10 | 2019-09-25 | Slgk Zakl Badawczo Wdrozeniowy Procesow Chemicznych Spolka Z Ograniczona Odpowiedzialnosca | Reactor for the production of fatty acids |
GB2558977B8 (en) * | 2017-09-10 | 2019-02-20 | Slgk Zakl Badawczo Wdrozeniowy Procesow Chemicznych Spolka Z Ograniczona Odpowiedzialnosca | Method for production of fatty acids |
EP3877355A4 (en) | 2018-11-06 | 2022-08-03 | Inventure International (Pte) Limited | Methods for making free fatty acids and fatty acid derivatives from mixed lipid feedstocks or soapstocks |
CA3153558A1 (en) | 2019-09-09 | 2021-03-18 | Ecolab Usa Inc. | Emulsion compositions for priming a pavement surface |
WO2022214950A1 (en) * | 2021-04-06 | 2022-10-13 | LignoSol IP Limited | Lignin-based compositions and related hydrocarbon separation methods |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US942207A (en) * | 1909-04-08 | 1909-12-07 | Isidor Kitsee | Process of treating the spent liquor of paper-mills. |
US2905604A (en) * | 1956-01-05 | 1959-09-22 | Absalom M Kennedy | Process and apparatus for electrolytically treating black liquor |
US4238304A (en) * | 1979-08-30 | 1980-12-09 | Raybestos-Manhattan, Inc. | Method for improved recovery of tall oil from black liquors |
-
1991
- 1991-08-20 US US07/747,547 patent/US5164480A/en not_active Expired - Lifetime
-
1992
- 1992-07-21 ZA ZA925463A patent/ZA925463B/en unknown
- 1992-07-24 NZ NZ243711A patent/NZ243711A/en unknown
- 1992-08-03 BR BR9206383A patent/BR9206383A/en active Search and Examination
- 1992-08-03 WO PCT/US1992/006390 patent/WO1993003815A1/en active IP Right Grant
- 1992-08-03 EP EP92917068A patent/EP0608244B1/en not_active Expired - Lifetime
- 1992-08-03 CA CA002115762A patent/CA2115762A1/en not_active Abandoned
-
1994
- 1994-02-18 FI FI940773A patent/FI940773A/en not_active Application Discontinuation
Also Published As
Publication number | Publication date |
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FI940773A0 (en) | 1994-02-18 |
EP0608244A1 (en) | 1994-08-03 |
CA2115762A1 (en) | 1993-03-04 |
EP0608244A4 (en) | 1994-06-14 |
BR9206383A (en) | 1995-06-13 |
ZA925463B (en) | 1993-03-03 |
FI940773A (en) | 1994-03-11 |
NZ243711A (en) | 1994-06-27 |
US5164480A (en) | 1992-11-17 |
WO1993003815A1 (en) | 1993-03-04 |
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